Removable lock for blade wheel assembly



R. L. COOK 3,042,368

REMOVABLE LOCK FOR BLADE WHEEL ASSEMBLY 2 Sheets-Sheet 1 Jul 3, 1962 Filed June 29, 1960 s 7 51 3e 5e 29 FIGJS RICHARD L.COOK

INVENTOR.

BY M 4 7 July 3, 1962 R. COOK REMOVABLE LOCK FOR BLADE WHEEL ASSEMBLY 2 Sheets-Sheet 2 Filed June 29, 1960 RICHARD L.COOK

INVENTOR.

United States Patent Ofi 3,942,368 Patented July 3, 1952 ice ware

Filed June 29, 1960, Ser. No. 39,698 Claims. (Cl. 25377) This invention relates to mounting blades in a blade wheel. An insertion slot is generally provided to accommodate the reception of blade bases for complementary abutment in an annular undercut groove. More particularly, this invention relates to a lock which facilitates the mounting of the last blade in the insertion slot so that it can be removed without damage.

It is conventional practice to anchor the last blade in the insertion slot by means of a pin which extends from one side of the blade wheel to the other side. This technique is perfectly acceptable when blade wheels are shrunk fit onto shafts. However, with increased speeds and as sociated demands upon rotors, designers have shown a proclivity toward unitary rotors in which several blade wheels are integrally formed with a single shaft. There has also been a tendency to space blade wheels closer together. Accordingly, blade mounting on unitary rotors presents a drilling clearance problem. This lack of clearance makes the drilling of pin holes both an expensive and a time consuming operation.

To avoid drilling clearance limitations various types of radial access joints have been suggested. Solutions posed to date have generally created more problems than they have solved. These nascent problems include a lack of strength under radial and circumferential stresses, susceptibility to vibratory loosening and destruction of the blade on removal.

The present invention obviates the above difliculties by providing a removable device especially suited to locking the last blade in the insertion slot of a blade wheel. The foregoing is accomplished by the combination of a conventional blade wheel with a blade lock capable of being disassembled comprising key means to provide abutting connection of said last blade to the blade wheel. The key means is engageable by relative movement between the last blade and the blade wheel.

A fuller understanding of this improved blade lock will be had when it is considered in connection with the accompanying drawings in which:

FIGURE 1 is a side view of a portion of a blade wheel with blades, spacers and a blade lock shown in assembled locked relationship.

FIGURE 2 is a rim view of FIGURE 1.

FIGURE 3 is a section taken on line 3-3 of FIG- URE 2.

FIGURE 4 is a rim view of a portion of a blade wheel showing the radial rim insertion slot and the undercut recesses formed in the sides thereof.

FIGURE 5 is a section taken on line 5-5 of FIGURE 4 showing the swallow tail annular undercut groove.

FIGURE 6 is a perspective view of a part of a blade wheel showing progressive steps in the mounting of blades and spacers into the annular groove via the radial rim insertion slot and also depicting the insertion of the last blade and its movement by rotation to engage the root key into the undercut recesses formed from the side of the insertion slot.

FIGURE 7 is a crosssection through the last blade in its locked position taken on line 77 of FIGURE 1.

FIGURE 8 is an elevation view of the last blade with the root key shown on the blade base.

FIGURE 9 is an elevation view of the last blade showing the insertion projection of the blade base.

FIGURE 10 is a view of the blade end of the last blade.

FIGURE 11 is a view of the insertion end of the last blade.

FIGURE 12 is an enlarged rim View of the blade wheel showing the last blade in its locked position and showing the disposition of the set screws and filler material.

FIGURE 13 is a section taken on line 1313 of FIGURE 12.

A blade wheel 21 is shown in FIGURES 1, 2, 3 and 6. FIGURES 4 and 5 show groove means generally designated 22 defining annular undercut swallow tail groove 23. Ridges 24 of swallow tail groove 23 provide restraint for blade bases 26 and spacer bases 27 mounted therein against every displacement except movement about blade wheel 21 in annular .groove 23.

Slot means generally designated 23 are best shown in FIGURES 4 and 7 to describe elongated rim insertion slot 29 including slot ends 31 peripherally disposed rela tive rim 32 of wheel 21 and slot sides 33 disposed normal to the axis of blade wheel 21. A plurality of blades 34 and spacers 36 with swallow tail bases 26, 27 are best shown in FIGURE 6 mounted in complementary abut ment with ridges 24 of undercut swallow tail groove 23.

A last blade 37 is provided to complete the peripheral blade arrangement and to peripherally restrain blades 34 and spacers 36 in annular slot 23. Last blade 37 has an insertion end 38 fashioned for reception by insertion slot 29. A novel blade lock capable of being disassembled is generally described 39. This novel blade lock 39 comprises key means generally designated 41 to provide abutting connection of last blade 37 to slot means 28 of blade wheel 21. Key means 41 is engageable by relative movement between last blade 37 and slot means 28.

The preferred embodiment of blade lock 39 shown in the drawings comprises undercut recesses 42 with shoulders 43 formed from sides 33 of insertion slot 29 as best seen in FIGURES 4 and 7. The preferred embodiment of the novel blade lock further comprises a root key 44 as best seen in FIGURES 6, 8 and 11 formed on insertion end 33 of last blade 37. Last blade 37 is disposable in its insertion position with root key 44 aligned in the long direction of insertion slot 29 as is seen from the phantom outline in FIGURE 6. After insertion, last blade 37 is movable in the shown embodiment by turning as seen in FIGURE 6 from its insertion position to a locked position thereby engaging root key 44 into undercut recesses 42.

As best seen in FIGURES l and 6 each of the plurality of blades 34 and spacers 36 has a conventional skirt 26 formed thereon. Conventional skirts 46 are formed to project above rim 32 of blade wheel 21. Before the insertion of last blade 37, blade 47 and spacer 48 mounted in groove 23 adjacent ends 31 of slot 29 are aligned flush with ends 31 by means of a technique well known to the art. A novel type of skirt 49, best shown in FIGURES 2, 10 and 12, is formed on the last blade 37. As is seen from FIGURE 10, skirt 49 has a generally square plate shape with two diagonal corners 51 rounded. As is seen from FIGURE 6, when last blade 37 is positioned in insertion slot 29 with root key 44 aligned in the long direction of elongated slot 29, the skirt 49 of last blade 37 is in abutment between blade 47 and spacer 43 adjacent ends 31 of insertion slot 29. When last blade 37 is rotated to engage root key 44 into undercut recesses 42, skirt 49 of last blade 37 turns in unison with last blade 37 maintaining abutment between blade 47 and spacer 48. Because skirt 49 projects beyond rim 32 of blade 21, slot means 28 defining sides 33 of slot 29 do not interfere with the rotation of skirt 49.

When last blade 37 is installed in its locked position, screw holes 52, as best seen in FIGURE 12, biasing rec- J tangular ends 53 of skirt 49 and adjacent blade 47 and spacer 48 are drilled and tapped and set screws 54 are engaged therein. Set screws 54 restrain last blade 37 from rotation relative slot means 28.

As shown in FIGURES 12 and 13 a removable filler material 56 is provided to complement remaining volume 57 of insertion slot 29. Filler material 56 is suitable for removal from insertion slot 29 by melting without permanent adverse eifects being sustained by the metal out of which the remainder of the assembly is made.

A peripheral band (not here shown) is then mounted to engage rivets 53 which are formed on the peripheral ends 59 of blades 34.

To remove blades 34 and spacers 36 from blade wheel 21 the peripheral band is removed from rivets 53 at peripheral ends 59 of blades '34 and 37. Filler material 56 is then melted out of insertion slot 29 and out of screw holes 52. Set screws 54 are removed. Conversely to the method outlined in FIGURE 6, last blade 37 is rotated from its locked position back to its insertion position thereby disengaging root key 44 from undercut recess 42. Last blade 37 is then radially removed from insertion slot 29 with root key 44 aligned in the long direction of elongated insertion slot 29. With last blade 37 removed, the remaining blades 34 and spacers 36 are moved about annular undercut swallow tail groove 23 to rim insertion slot 29 from whence they are radially extracted. Accordingly, by the present invention, blade removal may be ascomplished without damage to any of the blades.

It will be understood that the invention is not to be limited to the specific arrangement of parts shown, but it may be widely modified within the invention defined by the claims.

What is claimed is:

1. A blade wheel comprising:

(a) a rim on said wheel remote from the axis thereof and having a circumferentially extending groove therein,

(b) a slot means defining a blade rim insertion slot formed on the circumference of said rim and extending inwardly from the circumference in alignment with the circumferential groove of said rim,

() at least one undercut groove extending transversely in the circumferential groove of said rim,

(d) at least one undercut groove extending transversely in said slot means,

(2) a plurality of blades mounted in the circumferential groove of said rim,

(f) said blades having at least one projection engaging the surfaces of the undercut groove of the circumferential groove to restrain said blades in said wheel under centrifugal action,

(g) a last blade inserted into said slot means,

(It) said last blade having key means thereon adapted to engage the surfaces of the undercut groove of said slot means on rotation of said last blade to hold said last blade against radial separation from said slot means,

(i) a skirt means formed on said last blade to hold said last blade and said first mentioned blades in peripheral abutment on rotation of said last blade,

(j) said key means and said skirt means to coact to lock said last blade and said first mentioned blades in assembled position.

2. The combination claims in claim 1 wherein:

(a) said key means including at least one key member to engage the surfaces of the undercut groove of said slot means on rotation of said last blade against radial separation from said slot means,

(b) said skirt means including a substantially quadrilateral skirt member having two rounded corners in diagonal relationship thereon,

(c) said rounded corners of said skirt member to permit said last blade to rotate in peripheral abutment with said first mentioned blades,

(d) said key member and said skirt member to coact to lock said last blade and said first mentioned blades in assembled position.

3. The combination claimed in claim 2 wherein:

(a) at least one threaded bore extends into said last blade and the adjacent first mentioned blade,

(b) screw means connected to the threaded bore to prevent said last blade from rotating thereby locking said last blade and said first mentioned blade in assembled position.

4. The combination claimed in claim 3 wherein:

(a) a filler material is disposed in said slot means to occupy the remaining space therein,

(b) said filler material having a wider temperature range than the operative temperature range of said blade wheel.

5. A blade wheel comprising:

(a) a rim on said Wheel remote from the axis thereof and having a circumferentially extending groove therein,

(11) a slot means defining a blade rim insertion slot formed on the circumference of said rim and to extend inwardly from the circumference to intersect the circumferential groove of said rim,

(0) an undercut swallowtail groove extending axially in the circumferential groove of said rim,

(d) an undercut groove extending axially in said slot means,

(e) a plurality of blades and a plurality of spacers mounted alternately in the circumferential groove of said rim whereby one of said blades is adjacent one side of said slot means and one of said spacers is adjacent the other side of said slot means,

(i) said blades and said spacers having projections corresponding to the swallowtail groove of the circumferential groove and to engage the surfaces of the swallowtail groove to restrain said blades in spaced relationship in said wheel under centrifugal action,

(g) a last blade inserted into said slot means,

(11) said last blade having a key member formed on the end thereof adjacent the axis of said wheel and adapted to engage the surfaces of the undercut groove of said slot means on rotation of said last blade to hold said last blade against radial separation from said slot means,

(i) a quadrilateral skirt member having a pair of rounded corners diagonally located thereon to permit said last blade to rotate in peripheral abutment with said first mentioned blade and said spacer,

(j) said key member and said skirt member to coact to lock said blade into operative position with said first mentioned blades and said spacers.

References Cited in the file of this patent UNITED STATES PATENTS 1,156,529 Hillner Oct. 12, 1915 1,630,151 Werber May 24, 1927 1,687,891 Ray Oct. 16, 1928 2,918,255 McGinnis Dec. 22, 1959 FOREIGN PATENTS 776,618 Great Britain June 12, 19 57 

